Since complementary metal oxide semiconductor (CMOS) devices of 0.13 μm rule were introduced, Cu interconnects have been used in system large scale integration (LSI) circuits for the purposes of reducing interconnect resistance, suppressing or reducing interconnect delay, and the like. With continued progress toward further miniaturization, however, the degree of difficulty in filling interconnects, via plugs, etc. tends to be increasing.
Currently, to improve the filling characteristics and the reliability, it has been proposed to use, as a barrier material, Ru that is good in wettability to Cu atoms compared with Ta conventionally used.
Use of Ru as a barrier metal material is described in Japanese Patent Publication No. 2007-258390, which proposes use of a Ru alloy (RuTa) as a diffusion preventing layer 15 of a semiconductor device.